CORNEAL DYSTROPHIES

Question 1

list general characteristics of corneal dystrophy

Answer 1

bilateral, symmetric, and have no neovascularization

Question 2

list 1 anterior corneal dystrophy?

Answer 2

Epithelial basment membrane dysrophy (EBMD)

Question 3

what is the most common anterior corneal dystrophy?

Answer 3

EBMD

Question 4

what causes EBMD?

Answer 4

• Basal epithelial cells secrete an excessive amount of basement membrane that leads to thickening of the basement membrane and causes weak hemidesmosomes formation –> this causes corneal epithelial cells to be trapped beneath the basmement membrane and prevents them from progressing anteriorly.

Question 5

symptoms of EBMD?

Answer 5

• Asymptomatic – unless central corneal is involved then they will have blurry vision.
• Epiphora
• Severe pain if RCE.

Question 6

signs of EBMD?

Answer 6

• Map – irregular islands of thickened, gray, hazy epithelium.
• Dot – Dot-like (microcystic) epithelial lesions.
• Fingerprint – Whorled/concentric lines that look like fingerprints.
• Negative staining with NaFl.
• Possible RCE – due to the lack of hemidesmosome between basal epithelial cells.

Question 7

tx for anterior and stromal corneal dystrophies?

Answer 7

• ATs
• If RCE – Abx + ATs + bandage CLs
• if central scarring – consider phototherapeutic keratectomy (PTK), lammellar keratoplasty (DALK), superficial keratectomy, or penetrating keratoplasty (PK).

Question 8

what are 3 types of stromal corneal dystrophies?

Answer 8

1. macular dystrophy
2. granular dystophy
3. lattice dystrophy

Question 9

which sotrmal dystophy is autosomal dominant and which are autosomal recessive?

Answer 9

AD = granular dystophy & lattice dystrophy
AR = macular dystrophy

Question 10

which stromal corneal dystrophy is most visually disabling?

Answer 10

macular dystrophy

Question 11

what causes macular dystrophy?

Answer 11

• It occurs due to an error in Keratan sulphate (GAG) metabolism  that leads to an accumulation of GAGs

Question 12

signs of macular dystrophy?

Answer 12

• Central anterior stromal haze 
• Greyish white, dense, focal, poorly delineated spots –>
• Irregular corneal surface (due to stromal deposits) –>
• Increased in lesion size & stromal haze –>
• Increasing opacification involving full thickness stromal limbus-to-limbus.

Question 13

what stains macular dystrophy?

Answer 13

stains with Alcian Blue

Question 14

what age does macular dystrophy occur?

Answer 14

ages 3-9

Question 15

what is the most common stromal corneal dystrophy & which is the least?

Answer 15

• most common = granular dystrophy
• least common = macular dystrophy

Question 16

what are the 2 types of granular stromal corneal dystrophy?

Answer 16

• type 1 = Characterized by amorphous hyaline deposits w/in stroma that stains bright red with Masson trichrome.
• type 2 = Characterized by amorphous hyaline & amyloid deposits w/in stroma that stains with Masson trichrome & Congo red.

Question 17

signs of granular dystrophy?

Answer 17

Type 1 signs (in order):
* Small, white, sharply demarcated deposits in the central anterior stroma.
* Gradual confluence
* Hazing of intralesional space

Type 2 signs:
* Superficial fine opacities that appear like rings, disc, stars, or snowflakes.
* Deeper linear opacities – like lattice dystrophy.

Question 18

what is lattice dystrophy?

Answer 18

accumulation of amyloid deposits in the anterior stroma.

Question 19

lattice dystrophy stains with?

Answer 19

• Stains with Congo red

Question 20

signs of lattice dystrophy?

Answer 20

• Anterior stromal glassy refractile dots which coalesce into refractile branching lines (amyloid deposits).

Question 21

which anterior and stromal dystophy have RCE and how often do they occur?

Answer 21

• EBMD - frequently
• macular dystophy - occasionally
• granular dystophy - rare
• lattice dystophy - common

Question 22

what is the pneumonic to remember types of depositis and staining associated with stromal dystophies?

Answer 22

Marilyn Monroe Always Gets Her Men in LA County:

M = Macular dystophy
M = Mucopolysaccharide deposits
A = Alician Blue
G = Granular dystrophy
H = Hylaline deposits
M = Masson Trichrome
L = Lattice
A = Amyloid deposits
C = Congo Red

Question 23

what are 2 types of posterior corneal dystrophies?

Answer 23

1. Posterior polymorphous corneal dystrophy
2. Fuch’s endothelial corneal dystrophy

Question 24

what is posterior polymorphous corneal dystrophy (PPMD)?

Answer 24

• It is characterized by excessive proliferation & migration of of Descemet & endothelial cells.

Question 25

what age does PPMD occur?

Answer 25

age 20-30

Question 26

signs of PPMD?

Answer 26

* **Hallmark** = vesicular lesion -- that can also appear as linear & band-like (*train-track lesions*), or mix. * corneal edema * **Angle closure glaucoma** -- from peripheral anterior synechiae.

Question 27

tx for PPMD?

Answer 27

* same as anterior and stromal dystophy + treat increased IOP.

Question 28

what is Fuch's Endothelial Dystrophy?

Answer 28

characterized by progressive endothelial cell loss (hallmark) due to excess descemet's membrane.

Question 29

symptoms of Fuchs?

Answer 29

* Blurry vision -- vision is worse in the morning b/c there is an accumulation of fluid in the cornea while sleeping (stromal swelling) * Pain -- if bullous keratopathy

Question 30

what are the signs for each stage of Fuch's?

Answer 30

* Stage 1 -- initial manifestation of the disease is central corneal **guttae**. * Stage 2 -- Decreased endothelial cell density associated with **pleomorphism** & **polymegathism** & **stromal edema** causes a fine gray haze (<500cells/mm^2). * Stage 3 -- characterized by **bullous keratopathy**, which is epithelial microcyst that can coalesce to form large intra & interepithelial cystic spaces or **bullae** which can lead to epithelial erosions & fingerprint lines --> painful. * Stage 4 -- characterized by avascular subepithelial fibrosis & **scarring** between the epithelium & Bowman’s membrane.

Question 31

what is the min cell count needed to prevent corneal edema?

Answer 31

* A min of 500-700 cells/mm^2 are required to prevent corneal edema

Question 32

tx for Fuch's?

Answer 32

* Hypertonic saline solutions (Muro 128) gtts or ung -- for stromal edema. * ATs & bandage CLs -- for epithelial bullae or RCE. * DSAEK / DMEK -- for severe cases.

Question 33

are posterior corneal dystophies associated with RCE?

Answer 33

* NO!!

Question 34

what inheritance are posterior corneal dystophies?

Answer 34

AD

Question 35

why does stromal edema occur in fuch's?

Answer 35

endothelial cell count is too low which leads to compromised endothelial pump mechanism.